Integrated FP/RFBG sensor with a micro-channel for dual-parameter measurement under high temperature.

An integrated sensor via overlapping a micro Fabry-Perot (MFP) cavity with a micro-channel on a regenerated fiber Bragg grating (RFBG) is constructed for dual-parameter sensing of temperature, strain, and gas pressure under a high temperature (600°C). The MFP is fabricated by using a 157 nm micro-machining on H2 -loaded bendinsensitive fiber. A fiber Bragg grating (FBG) is inscribed at the same position of the MFP using 248 nm laser exposure, and then successfully regenerated after a required annealing process which enhances the strain sensitivity of MFP more than three times. The micro-channel created on the MFP is used to improve gas pressure sensitivity of the MFP nearly 100 times. Since the MFP and RFBG have different sensitivities to gas pressure, strain, and temperature, the sensor head could be used to perform dual-parameter measurement by simultaneous measurement of high temperature and strain, and high temperature and gas pressure.